1. Field of the Invention
The present invention relates to an antenna module and more particularly, to a dipole antenna module operating in a frequency range of 2.40.about.2.50 GHz for a portable computer.
2. Description of Prior Art
Today, more and more portable computers are being linked with other electrical equipment using wireless telecommunication instead of cabling, defining a WLAN (Wireless Local Area Network) for exchanging data or other signal information. Wireless communication requires that a portable computer be equipped with an antenna module capable of effectively transmitting and receiving electrical signals. A prior art dipole antenna consists of two aligned antenna arms which can only transmits/receives signals in a predetermined direction. This limitation hinders the performance of the portable computer, which is intended for use in a movable application. Furthermore, the performance of the antenna is affected by environment, wherein many sources of reflection may be present. Moreover since the size of the portable computer is of primary concern, the size/volume of the antenna should also be reduced, in particular, when the antenna is located at the corners of the display or body of portable computer. U.S. Pat. No. 5,677,698 discloses an antenna arrangement comprising a slot antenna element. The slot antenna element is located between a dielectric material and a ground plane. When two slot antennas are used to form a diversity configuration, they are connected in such a way that only one antenna which receives a stronger signal will be selected for use while the other is not. The use of two antennas wastes valuable space in the portable computer and is costly.
U.S. Pat. No. 5,966,098 discloses an antenna system comprising a dipole antenna having antenna arms of different lengths, and an impedance matching circuit provided for electrically connecting the antenna arms to the device to increase the antenna gain. Thus, said antenna system not only takes more space, but also has a complicated structure due to an additional impedance matching circuit.
Hence, an antenna module is required to overcome the disadvantages of the prior art and for use with the proliferation of WLANs.